SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f2fb423af043cb4984c0a34049f596ad7d168c39162d609d514aa4a88042f3ec' 
  AND token = 'dLq0GvmKdS/rOew4Rtjlz9aQ/uCJZCP+qfTTE3Ih13g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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