SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7e621e0d414c5525cfc1332858b997f3addd1041c3b3329d872cd0674facf290' 
  AND token = '/QspTtAg7yF3eYgUCJihXqmMVYjnZv26WSLcBFGm2hE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}