SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fe00c97fb56a2e4fbf8055de516775e718dfb55be955925f3f8adc12420908cf' 
  AND token = 'q72szpfYrzcmddCXsuMzQkLdQoMVDVY41si8FAohLAM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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