SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '321dd89a16fa9345cf699f1c8d3d906a53245c6a05962f5467b3948cda14f352' 
  AND token = 'Lu82zpZqYxW3+DjfnRLSSwAhDUKgkZ3WKD6xHXuGDK4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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