SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '304d4ed43852259097ec1b55d0446917a596df8873433daf26ce02b29b7ea6a4' 
  AND token = 'S1UbwbZMBKyEc36l76rsxnpAKJZqUllZKSfsbP7NsEY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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