SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '620a8a6c2737b48a2b865d42e619ff934a15603f96618d3f09e7c3648b6d364c' 
  AND token = 'felW+JlnVqeWHLi2Jkxo3qb8RSE/zZPWyhpTqAlklSk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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