SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '876b42258882a81b85d2215b4100c8d0dcc08a535d3e4cf17f357749dffa5971' 
  AND token = 'Vuj2M1D8n4oP6D3baqZGcAFHAjmWoHgKcgqYjBRLKV0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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