SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7268aff191621c597c70cc58af28e2072c4fd368707d54de0749057875c4b3dc' 
  AND token = 'xgQCaugpETZ1zRmDEh1oOQYmJ+xFdXUtDmEBXFAWXBA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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