SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cd937a1d84f536947311bbb9b8256267d39e36004d5ef0eb08d1778637ac2abf' 
  AND token = 'REYVzm+xBbJRvUeeItQoo2ez/XMdERejCRGNlxLsCK4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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