SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71a954d794626ac5cbeb1274fa85adf6ee9504c1e2820da22b2a492542f9be35' 
  AND token = 'VMOlMBQw3K4ew64PTO4hm6ihkXW40Ih66fvzI3zhiPc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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