SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f6849ddcec007e3a80b70d65a5911b73985970254470b5b1900f1b146c652104' 
  AND token = '0Cd/126X96hGv/xpzvEBI2+Nm1pF71+H9Ygjfqzefvg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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