SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '07516acd1530452291baf23b79bfdeb04c4a7173e926a9a16519d14118350352' 
  AND token = 'UcFt/jFVcLkAg+nEafxhmJqDLaHBN3GvzgG3vLN3hPM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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