SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '34f3a91af4726192aa1744a8bdfc630fe2ca7bf059ee5eec423ee22ea0af7f93' 
  AND token = 'W0Y3fVVGCE5/2FLWU6aVQSGT539lBrz955YoEziALkY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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