SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76d98fa6599b528af3fd799441982109e3910d7affe669f0b8f615c4c771b6d4' 
  AND token = 'Yiqw0NQmAWyqMejIGEkjx0ZNmrBI5uPgAmmyYjiVvm8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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