SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1892632f9c18d1da3b42bfe388068c7fb5b4b5da0360c95cf6d74ca34e7d5e6f' 
  AND token = 'UGJYwXdsArdMYOdgAycBFaAfltMTdcEaoFwnSEmUIsI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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