SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5ab6bf311dd86563addbf7109589b6b3c409c66f94bdb126a062441bda136f75' 
  AND token = '+rOY4SGjOfPKVBVULaqHutUrcyvPw08Gvd1Mj1fAeQM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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