SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '912c7390b02d6f732f1f302d876f7992f60a914636c8c0655b15301b33c21e9c' 
  AND token = 'vcaW6g0qD6rJvGoV1h3g7WZPpquPXwbY+fAfKiJsVSo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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