SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8909d810e741cc4ea2ead310534664ec1343e99fccfd53e60b291fdd876ee2cf' 
  AND token = 'qVrym8DY2FzxedyYS5wrTJHLqFfaB17slOgelat+5H8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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