SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7cf8f5147932c786d944d78a6f50ac8d42a2041260398c936723ca74c352cafe' 
  AND token = 'WEQcJRtyU/ReSn4f+3xxFYX98Ey1uxxSXzfKArTEU/g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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