SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd4c2655b562f66be95f0dc008d98291af7a9a1fbe774aeb45bcc2b2674cbef78' 
  AND token = 'HSz7DDu+VJphcK6p/fwC3aYEFTysEYNZxFElzTArJjA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00053

JSON explain

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