SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '904f74034637dd8e403c0e2453241479a364bdecd3dab02a7a4a33993f63ce4d' 
  AND token = 'bO5Mxsy4sYOnT98MUA/IN+hbVwrDZJ1CdGoulwNalKs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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