SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5cdc52194bef3fa06ac15123e5c820ea579849a5125a030cf27077680b55762b' 
  AND token = 'n7+nAiO4nqaM9JWLkYCvHCI8VXfgbwW9ZHZhpAo4DjY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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