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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b12f1d49659d442806f168175710eb94403501b15c9a7e2d115c5cc1e8cb0e90' 
  AND token = '0WldDb2MrodBcH1kz3z106+msdyRiSsRYUdN3yfHay8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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