SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ea8dcd266f766ff3582b504ff15d5dcaefc76d27c43bd84636c1eed3eecc1e5' 
  AND token = 'W3Hl9RNw3hVeBN1dGbliHlUEsnT7gE8WaVF0KThE/yk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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