SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81d510040b0b9073bfb3afe580bf1f350e48da5729eb4da9a166b705fe60116b' 
  AND token = 'Cze38hszKCxoDsoTUPS1dva0YmcokEZYUcRfcYRGPqI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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