SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2a2e31d626957681755bb7411206bbed3020251ef7dfaac48e9412316057f833' 
  AND token = 'xu+ErREsx68YiMTXRXcTlv2xgpNhQ8+6mrYuxQLQLSI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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