SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51842c2393ab8ea5a367746ac22c3c73aaab2ca888be26719dacd765612fd762' 
  AND token = 'YEWiUNR5B655AwZfH0oWjWd/1gD8RzSHnsviziHqs7c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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