SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50a53799ca765df6ed7d51f902b313b08fe925c91c30657f0619e9121efc935e' 
  AND token = 'mHm+a312S/4vHVmEy9r9ef0oLud8KcjT4O0IV3GaenM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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