SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f62e82d76e44169339f01c1008bbcc146dc625f3be942b4fcad7e811e2b0243d' 
  AND token = 'gnxZMUHY+jRcZvyYOmx6b3ID4cxIGGC7OtEXqPbjIvY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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