SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3e65ff83eb327602a8221263a9c0f23dd94849789bc2d31e754ae79d02094c78' 
  AND token = 'g5ipRCuKuwWjjZEnoBmq14y4jTJFgWzhWbBqWLwd0aQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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