SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '31a489baf08562601d571ec97dfe55d2986a9bb682bb5cd88fe78df3a7e87694' 
  AND token = 'rV3Hjz+MyZlQzTZYzvOfljDaZt3j9+NsU5HKlynwKk4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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