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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '712786faf3bd1d35ce72a147afe3c3d75d1e8689d510c6d0cc32f4974b726279' 
  AND token = 'JWMgkcHgqrYK1aMKIsXxbfRP2vlZ9U9A4dUMXqUgq7I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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