SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7b973f218504ea6eaaea094e984187d892629c2dbb1540ff39d30ebb436cb9fe' 
  AND token = 'I+jVWcce1AVWzKpBjnfDPmIdLVQPNlUrFv7tJIjWCMU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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