SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '80f63c28da52060bbeb7d43f11d286f143f9d365bc274f88fd41b057c5eb3896' 
  AND token = '+FkES2SGI+MEjSOUCpVvvQxhfNVRpzpN3/irdxQpwE4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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