SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dbe9860acf948383dd47c6c73199aa0a36a755d55cba2d0f547e29304b09a320' 
  AND token = 'cEa0SxK4gwUahrpNjJJAXVzDexEihuhw3m5ST1L0oIk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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