SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '94c99a2baf0641879047b0cdf248dad004b51681ecfdfeec094a1945914d8b13' 
  AND token = '1ThmNIxdzXhxQbjiOGRpuSvxl3+YJPYAT46vTx4pKXA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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