SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '576ce4ed900297a08357580fd4de5a81858618b47119678a22dfe10f2262740f' 
  AND token = 'BjZ/UhQt1DfUHmuUzrKK7XCNNaW7STpmoLuQJk1Gt6Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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