SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8592aa90be6bce510952b5f2e981ed9c0364822ab6414e84d3590e44dce993bf' 
  AND token = 'qn56mlXzBPgbwkgRVG+c4QTdy/WoyPjfKMYI0dBuQ7g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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