SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7ee3f1b6bb3dab38a852339c17c99a349cb4d2d1f9d50c2d170fed5de833a593' 
  AND token = '6uZCz2jFqamhVt5VCBLqzg06SJKn4qEybpRSAVeXB0g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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