SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '20283069b0f87a6cb8d643043780e6965688db58b52b17b44fd643693424145a' 
  AND token = '3dX97iObWYfCEcPdSVS2XDYBEV9VzC4wsvZqeNNZ68o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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