SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ec18f39b0f76974c1956cc2c1c8cc01e1587b25179844c3ee14612472709a049' 
  AND token = 'EpFM016e+AgFOi46A6C5E9nBqwFPfyUs2ERJsDkq9Ys=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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