SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b51472a2bd6c289378e198d75ac16de730b273052384f718e1a5ef0dd30e4cf3' 
  AND token = '4Hu3TBgb7IGwWBbbYQVCNslEUJjVvFivYJMZJK2VQ4w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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