SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1df6b3a9813a79be0be8fdf721cc1e794c5d5d43ce7da8b0bae763ca94402c80' 
  AND token = 't6hFbGVSztN0SmBVpBEBsTumP1RVUbuS19jc2n/Lzg0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}