SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '66751a4f258c889e8cfbc22e9065e07c398088c620c4bc66bd10b5f35f4b7c39' 
  AND token = 'f0CoCKjqAJQvfyI5FFieNDpBGGmca/fO9zHjBZGsIs8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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