SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8ac142d41682a96a7eed60813bda0e03f7748bf0b03a2f73a783038b9bf4ea9' 
  AND token = 'fQVywDPn5XsR+jhm/P8TygHMMMh35K3LMkveusvNR4s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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