SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a3c900b1c9f53347b8da9915842132638dd0e9bad6b5383893ccece88b9a5ba4' 
  AND token = '26BqBEsdEKEEFP0WnGwTJB6+s/nkP6oGOQW8ew2wP5s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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