SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2d6988adf090a7108a7a5afbfe6d2fe61c15d9b46ad70629592dac4c6bc80e52' 
  AND token = '1o3437KtsNrc5UCdTnyRKOQD4eXKkfHTOgLW7wduXB4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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