SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4624ed99c502de1c761c8e762b29d2999639233b5db17703fb3144de41d61f15' 
  AND token = 'VpaTrsg6tIhhcjMZhrYWtp34CWnz5FjTc66PMWEPkfQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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