SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42ed288462e873e229d3a2ea209f51418b08894ac47de668e8b66761a846afd8' 
  AND token = 'g6KCURyWqfxT3PcHrjsxWs5qX5KwSDVKmLIVlAh206M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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