SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '850686a81986af6c3f5e9d775b57d943dc3d031059f737e6f6ad1f79d901a8c0' 
  AND token = 'yXQEHAVABQ2UuLcPDIL8KIxdBm+1d2ENqzwel9AX6UA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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