SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '018923d29a91ea3dac2990d1a9a0c040bc8d8b4ed6bcc2d0e0141874bded7e3c' 
  AND token = '4pcrRcVIZiDMgZ+ejIh18oU8TUTvjRJjZ0gPG86QOuk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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