SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2b298cd62b0b7fe7d4772e14f02a5840c1570293d0a6f2f03117406242b36656' 
  AND token = 'iFhEkNnu+lbmaUeIgs0yngsF3YIHWmmw8LFJyx0p0VI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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