SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8a8e60dd92a0440b06baf04917143e1ccdf669551a45bb83f98e680d353c7a9' 
  AND token = 'MHyvkm7sciT+xU39Ym2mfOrMi/Xjq+eUh1CRMpc7BEg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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