SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1204ac0a53d3e723463af626d39928369d5a69e5c5079120a8533c88d5efb358' 
  AND token = 'xaDIexyKWRwo1T4wiqXzHoBZpRZDPq80fiDyyt9daeo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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