SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8949efb447b69ce63aa71d73d7ab449197ce8d9c568bf4a2fb13cc585e0cfb7' 
  AND token = 'iSuuPrZTJwmiTJQU+CAGkdKfvAUKPZsHpIfQ3cTpqxE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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