SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '821fd10cfa1496f1da7ac16a4f5e40191a3716f574c1a67b809016e7e0b51866' 
  AND token = 'FuGhk473f0HzQHDJDaj1imG2lnO1OXdq729P2VCZY4U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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