SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9b234be5e6e5ea73465eb8b6a0ef937c075a63154b33233c8a30208e7be08ed6' 
  AND token = 'JXiHI/jojV7Wx1UJ5ktUXEqaLeLzZrWOtXB37p3vgQw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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