SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b59da21ecc9d4002f4eeb3e60545c957ffdc738ae579294455dde0f9d40bd4e3' 
  AND token = 'fuZrlN/dEEkHquJleFCtL8bBazxSBA4jhiT5f+8okS8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}