SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b48e1998f7b445165cfb102576bbf2862897d1c3a8757afd2abed6674d41dd25' 
  AND token = 'mnKW+RVXvPZhaeOAHI0biljTYGxcRDcp5ETMp2HBgt4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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