SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '364e2ea3c5dc50434f6aac84a117231e6619ae46d9dbb48f1782c7a6ef872277' 
  AND token = '+bfgDENU1igjMTQnUdNIu3MrSNsXwXTWTJywzWUAJ9E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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