SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a436ff183c3ed77b259542b0a437ef0c996555f57f6f43d862bf6d12b8b6a88f' 
  AND token = 'HPFFQ12/Opm7JB80uBKDRm24EwViqCrON+nQaYdQAAY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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