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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'db578cb9d57840d4f8b65d8541381b3517179ca2da48a7eb9f0370e790cc8edb' 
  AND token = '+Dzr9VTeyOYNIwyz36tZiBWfT7/QGck2DnR2aMQXxYY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00054

JSON explain

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