SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6cb8b9aa4b9477fe22341c61d45c04b080f8d34f78f05b0cfa9496b723fcf29' 
  AND token = 'ZaC4rXIr1+KeY+DPW3aDAm5sZkXJybWSeh0QSCPPnYw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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