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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9a1e5eee68704dc673fa25907a3cf7944e6b09178b0abe28d01fa781f48c5a2e' 
  AND token = 'eJ40AwsvhIPE2dJe3dLJ0Zh2OmXQaLnevTELuhBJY1Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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