SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51171ded39efec157c3b5f6f29a513364d3ebb1f9b291c9064858c99e62d5db6' 
  AND token = 'TzYYn3GQ/hW84AMR/CsWN2URKygZ0EsRSktf37T8Tnk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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