SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8539c4860ce198f1708392b73835c26c156793ca7234e23027425f6f1811ef3e' 
  AND token = 'JPgStnml4fpz+AaHBC6KTA0om6p/R4ZyBCCTxDROifo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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