SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6a406d68de9e2c947837abe7155fa38dccf678dc75562a4c51683ac17dfbc68' 
  AND token = 'NnfTrPrcJwQWpr/njBauYQCmPaYDQAn0D/Hd8r4wzIU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

JSON explain

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