SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4088ad3a81251f273dd9b1012a598b42091f6bb738628f8eafbc9f623282c9da' 
  AND token = 'a/J5PDPUk6pRxIIwZlCEu7nuxZGjtcqZ4NxqDAEttjw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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