SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '88d6a664a54cfbdd03c5e6485779ee7aa48122621be2ccecbebbb0e91a9dae02' 
  AND token = 'iIW2cBmAFwOtCCR3vXfrvDrTUTSz/r75EiyfTGGpOZo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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