SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71ae2bdca93335064af7ee704b706b89093931035f890f9596a6dc8e157e1bd5' 
  AND token = 'L3L+iWt08XjqdSwwLzUfJeWDafHXaMuQJntFj9m1qjo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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