SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8021a9ff4f8210537fccdfee7b2528b316b14cc28b4ec558fe948439c51c635d' 
  AND token = 'ASxvhvptWl1woF+6Qbp3hF/rDcLAPVjJBajDTWONdDk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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