SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '38e7d386430d85a8268847b278b1d8490274b89ccee4acd38d6ca1d45e27929b' 
  AND token = '6FNQwII/6QgEPRlgZneF//PAAqMuWhwca/C6TJF0qdU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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