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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '634e44367bbd419387d210c4f169d1af6fba40fbf5978be379cadc1368215231' 
  AND token = 'WRQgr621L2FudrNc9x1fVB6/nrEn7S0+Y3fvtMYDOFc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}