SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '02513e50d167296ed51d8037edbb070c516608e792a1dd51460e5f4381be89ca' 
  AND token = '7FLF/1E5mmVahriytcDnICCujAS3yZDYDjT2sTjX1hU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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