SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1c8840293e66b35d57852d420abb05c7f2a73296b042ce79f195a15fe8613aa3' 
  AND token = 'LIJpbjEHCE4NgcnZsXRqvTcJwRARVUpZVgePgWHIins=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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