SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '3c4447b6de77ffda185143d444344d57c7dfb53fb53ad9b548c3090e7f2af3a3' 
  AND token = '50T3X7dEWWYF8+7eeIAvxEiELuVkCd9rFEcj/PFgNRQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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