SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '293e6ecf9f8e66047f9708b9bd302901d18994edff841cfd95ad34fa76ec0cad' 
  AND token = 'XFi6Bbhc2g/zVSn9YSR3LeyB1/Y3jSjaHYTWGpUAhXw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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