SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '3373fe3dd835afe51d297fbcf66cb641727f334a9821f03c9c376ce8c29f02f2' 
  AND token = 'TgFePVetyoRDo/hzuVN1YZq5fzh45htiiFfgGSIDVxw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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