SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'bc3962882b4146167fcec618f7731641fbec89d525079d76128c5705c041f265' 
  AND token = '/8VrFA5sLg5fqwkFvVq7BzynDyqRChEugBUgDM4eed4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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