SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9bb8f1c2f0b8188595a170f215034554962a76253850741ec0778461c7e4dcb9' 
  AND token = 'sTR5Kh+3cZLEigwtX3RQGWjzIFvZVW+VgALP861y+XU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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