SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'df6c8645b33232824368bdbdb7836185bb300c3261f83b049ef86b91c4531b87' 
  AND token = '1vU7K+nl0dU15XNSBJCR1nnz7fBuzkOi0emzdZru5mk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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