SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1d6dc14969108992546deb140731141da9771e1f2078f4f0e8c66bd4ce540254' 
  AND token = 'iuZ4qri3htlZMBg2dZPX1TuABs4VngYhWY575a9lO5Q=' 
  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"
    }
  }
}