SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a9c5c12520121619362ae0e388d75485568cfe6973926bd42f53e8207a8ceb8d' 
  AND token = 'DCBkrqyVF4hShTsRVQtv04OwN6ZbmLkAsYKx8AdFaAE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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