SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '53ffdbc5602a391004d47fd9a3870a982794b80508980df56098e7ca9b944d51' 
  AND token = 'O3xxYdm/CCyjZJQ5e3yIoK/5/pr9t1ukZMwC1c6QFyA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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