SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76f0854a848c34a4de0fae5d244821f6fd232e86d9d68a8586c9347b99ff2b90' 
  AND token = '0LjLDxJeS6cEqBOaIhQ4FzFVYVYT57cCz1RNwc44/h8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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