SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71d7017fee70108a1e02677fb4358b3133b44611ba4034d4be63b2344ef58963' 
  AND token = 'WHa+3YCfdFw4XSrxZLGqnZH/7hckg1BQ+nIj5HvRDMA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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