SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '377a451df334ea9624014337cb04cb7256107dc749817880cb6c0c09871070c7' 
  AND token = 'FHfKqJ0nMMC/Ht/9xQmGvZ1qPL0yzKVIwtNC+m/J9YQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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