SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '6f3fc49ff5c315bef93184a7321491407be06783b4a444b050fd14aa8083773b' 
  AND token = 'weNkBkeh78AGEm//fXbuRkDzKAoULbcsoBbCdMgXS80=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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